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CONTENTS
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Fire Pump OCPDs
Maintaining for Energy
Savings, Part 1
Electrical Troubleshooting
Quiz
Motor Windings Speak From the
Grave
NEC in the Facility
Safety
Answer to Electrical
Troubleshooting Quiz
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About This Newsletter
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This twice-a-month
e-newsletter is brought to you from the
publisher of EC&M magazine. MRO Insider addresses topics such
as:
Working with management and supervision
National Electrical Code® on the production floor
Safety procedures and programs
Troubleshooting techniques
Equipment maintenance and testing tips
Managing motors and generators
Trends in training and education
Managing energy use
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Maintenance
Fire Pump OCPDs
Overcurrent protection devices (OCPDs) normally protect
equipment and conductors from overload. With fire pumps, this isn’t
true. Fire pumps must run no matter what (almost).
To prevent saving the pump from overload while the building burns
down, Art. 695 requires the OCPDs to be capable of carrying the fire
pump motor load indefinitely.
Fire pump OCPDs provide short-circuit protection only. The
pump can’t run with a short anyway, so you aren’t losing pump
function due to the OCPDs. You may even have a chance to restore
operation.
You can’t protect fire pump conductors from overload with OCPDs,
so
prevent overloads from occurring in the first place. To do so, maintain
the system per NFPA 25 and ensure it conforms to NFPA 20.
If you think the OCPDs might be oversized, review OCPD sizing per
Art. 695. Obtain approval for resizing from the Fire Marshall (and
other
applicable AHJs), to protect your insurance coverage and your
facility.
Maintaining
for
Energy Savings, Part 1
The focus on energy savings seems to be on lighting,
with little said about maintenance. This leaves money on the
table. In future issues of this newsletter, we’ll examine how to tap
that particular piggybank.
However, before we do, let’s address a common misperception in the
lighting recommendations and coming regulations.
It’s true that replacing old fluorescent ballasts and lamps with
more energy-efficient ones reduces energy waste without requiring a
lighting redesign. But not all lamp replacements produce such positive
results.
Whether you save energy by replacing incandescent lamps with CFLs
depends on the application. It takes energy to make gas fluoresce. Once
it’s glowing, it uses much less energy to stay glowing. An
incandescent lamp requires more energy to run, but much less to start
than a CFL. Therefore, a CFL has to run for some time to “catch up”
with the incandescent in terms of total energy savings.
For momentary lighting, such as in a closet, incandescent lamps are
more energy-efficient than CFLs. Just slapping in CFLs won’t
necessarily reduce energy waste. When relamping, consider usage and
technology.
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Repair
Electrical
Troubleshooting Quiz
Your fire pump runs for no apparent reason almost
daily.
Unfortunately, that across-the-line start throws all kinds of power
anomalies into your system. Your power monitor shows additional power
anomalies when the pump shuts off. The toll on electronics is getting
management’s attention. What should you do?
The motor shop informs you the bearings are severely pitted. What
problem is this an indication of, and what condition is most likely
causing it?
The answer to this question appears at the end of this
newsletter.
Motor Windings
Speak From the Grave
A repair is complete only when the failure cause is
identified and corrected. Motor windings can tell you what the failure
cause is, if you understand the language they speak. Their vocabulary
consists of burn marks, broken windings, and debris in the
windings.
- Burn marks. These indicate a power distribution problem
that’s degrading your winding insulation.
- Broken windings. The usual cause is excessive thermal
stress.
- Debris. Debris in the windings typically means you need
better housekeeping around the motor. Examine the debris closely to
determine its source.
What about “cooked” windings? If all of the stator windings
look “aged” or “baked” from excess heat, then you have voltage
imbalance. If only two-thirds of the windings have this look, you have
single-phasing.
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Operation
NEC in the
Facility
If your site has hazardous locations, have you reviewed
them lately? With changes in configuration, materials, processes, and
equipment, area classifications might also need to be changed to
avoid:
- Incidents. If existing procedures are insufficient due to
underclassification, then your company carries undue risk of an
incident.
- Underinsurance. Your company may lower its financial risk by
upping coverage so it’s adequate for present conditions.
- Overinsurance. Your company may be able to lower its
insurance costs based on reclassification of one or more areas on
site.
Article 500 provides the foundation for understanding the hazardous
location requirements in Articles 501–506. Take time to learn
it.
Safety
In its early days, infrared thermography cost far more
than it does today. Even then, the benefits easily justified the cost.
One of those benefits was improved safety, mostly due to not having to
manually connect test leads.
It’s important to understand that thermography, like any other
electrical work, is not inherently safe. To conduct thermography, you
must open enclosures and be exposed to various dangers, such arc blast
from equipment on which you’re not even working. Today’s
thermographic cameras have many useful features, but arc blast
protection isn’t one of them.
NFPA 70E tables are based on the energy levels present in the
equipment being worked on. Nowhere does NFPA 70E say those tables
apply,
“…only if you’re holding test leads.”
NFPA 70E tables also apply to plant managers and corporate execs who
are tapping away on their Blackberries while “observing” the
ongoing
work. Arc blasts don’t care what your title is.
It’s best that nonessential personnel leave the test scene —
period. Internationally recognized safety expert Paul Hartman,
currently
with Power Testing and Energization (an electrical testing firm),
advises nonessential personnel to follow this simple safety practice:
“Don’t be there.”
Quiz Answer
Answer to
Electrical Troubleshooting Quiz
This problem has a 3-step solution.
The first step is to determine why the pump is operating at all. If
there’s a leak in the piping, it’s better to discover it now than
to
have a pipe fail during a fire. Contact a qualified firm to test your
fire protection pipe integrity. In an actual case of this problem, the
operators were using the fire pump system as a source of washdown
water.
Don’t permit such use. Testing or flushing the system is one thing;
using it regularly for non-protection purposes is another.
The next step is to determine why the jockey pump isn’t making up
pressure. Check the controls for that pump as well as for the main fire
pump.
Your final step is to reduce the severity of the power anomalies.
Check with your local AHJ and your insurance company about the
requirements for installing a softstart on that fire pump (for example,
it will need a manual bypass). You will need an engineered solution, so
be prepared to spend time and money to get it right.
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